The successor to the original three hundred, the 1956 model saw more horsepower more gear boxes and more success at Daytona beach with a new flying mile record, 139.373 miles per hour. The C-300, introduced in February 1955, quickly established itself as a force on the race tracks, winning 37 1955 National Association for Stock Car Auto Racing (NASCAR) and American Automobile Association races. At NASCAR's annual Daytona Beach Speed Week a C-300 averaged 127.58 m.p.h. (205 km/h), beating the second place Cadillac by seven m.p.h.

The 300's racing fame gave all the corporation's new "Forward Look" cars a shot in the arm. Approximately 1,700 '55s were sold during their short model year.

For 1956 the 300B received the corporation's raised rear fins and Chrysler's new 12-volt electrical system. Displacement was increased to 354 cu. in. (5.8 liters) and horsepower to 340. An optional 10.0:1 compression ratio pushed horsepower to 355, just over one horsepower per cubic inch. A new three-speed "TorqueFlite" automatic transmission replaced the two-speed, soon developing a reputation as one of the industry's best.

The 300B continued its racing success, and hit 142.9 m.p.h. (230 km/h) at Daytona Speed Week. Chrysler sold 1,102 300Bs in a soft car market.

It was 1955 that the first Chrysler 300 (C-300) was offered. It had Exner's distinctive styling and the 331 hemi. It was called 300 because with the Carter 4 barrel carburetors, solid lifter camshaft, and a larger-than-usual exhaust, the engine generated 300 horsepower. It was the first modern American production engine to do so. The car had some other distinctive features: it had extra firm suspension, which allowed it to be lower and to corner far better than most cars; and it was very luxurious inside. Leather upholstery, PowerFlite transmission, well designed instrumentation, and high performance made the C-300 the "gentleman's fast car".

And fast it was. Tim Flock raced the C-300 at Daytona in 1955, winning both on the road course and the flying mile. The 1956 model, now designated the 300B, won both events that year as well. In fact, the 300s dominated NASCAR tracks in 1955 and 1956, taking the overall championship both years. Those triumphs created the legend. The 1957 300C did not compete in NASCAR track events, but with its 375HP hemi engine, again won the Daytona Beach flying mile, making the Chrysler 300 the fastest American car for the third straight year! Simple strong lines, excellent engineering, a high level of luxury, and outstanding performance made the "letter cars" the most desirable of the Chrysler line. They became known as "the Beautiful Brutes".

Counting through the alphabet from the 1956 300B to the 1965 300L (there was no 300I), they were fitted with high-performance V8 engines and, for a time, ruled the great horsepower race. They introduced the latest innovations: Cross Ram dual quads, new suspensions, limited-slips, swiveling bucket seats, center consoles, tachometers, pushbutton automatics. Chrysler's 1955 300 won 23 of 45 NASCAR races. The 1956 300B came with a 354-cubic-inch Hemi engine and won five straight NASCAR races.